kernel/linux.git/fs/jbd2/checkpoint.c, branch v6.6.141

jbd2: gracefully abort on checkpointing state corruptions

2026-04-02T11:07:26+00:00

commit bac3190a8e79beff6ed221975e0c9b1b5f2a21da upstream. This patch targets two internal state machine invariants in checkpoint.c residing inside functions that natively return integer error codes. - In jbd2_cleanup_journal_tail(): A blocknr of 0 indicates a severely corrupted journal superblock. Replaced the J_ASSERT with a WARN_ON_ONCE and a graceful journal abort, returning -EFSCORRUPTED. - In jbd2_log_do_checkpoint(): Replaced the J_ASSERT_BH checking for an unexpected buffer_jwrite state. If the warning triggers, we explicitly drop the just-taken get_bh() reference and call __flush_batch() to safely clean up any previously queued buffers in the j_chkpt_bhs array, preventing a memory leak before returning -EFSCORRUPTED. Signed-off-by: Milos Nikic Reviewed-by: Andreas Dilger Reviewed-by: Zhang Yi Reviewed-by: Baokun Li Reviewed-by: Jan Kara Link: https://patch.msgid.link/20260311041548.159424-1-nikic.milos@gmail.com Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman

jbd2: prevent softlockup in jbd2_log_do_checkpoint()

2025-08-28T14:28:36+00:00

commit 9d98cf4632258720f18265a058e62fde120c0151 upstream. Both jbd2_log_do_checkpoint() and jbd2_journal_shrink_checkpoint_list() periodically release j_list_lock after processing a batch of buffers to avoid long hold times on the j_list_lock. However, since both functions contend for j_list_lock, the combined time spent waiting and processing can be significant. jbd2_journal_shrink_checkpoint_list() explicitly calls cond_resched() when need_resched() is true to avoid softlockups during prolonged operations. But jbd2_log_do_checkpoint() only exits its loop when need_resched() is true, relying on potentially sleeping functions like __flush_batch() or wait_on_buffer() to trigger rescheduling. If those functions do not sleep, the kernel may hit a softlockup. watchdog: BUG: soft lockup - CPU#3 stuck for 156s! [kworker/u129:2:373] CPU: 3 PID: 373 Comm: kworker/u129:2 Kdump: loaded Not tainted 6.6.0+ #10 Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.27 06/13/2017 Workqueue: writeback wb_workfn (flush-7:2) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : native_queued_spin_lock_slowpath+0x358/0x418 lr : jbd2_log_do_checkpoint+0x31c/0x438 [jbd2] Call trace: native_queued_spin_lock_slowpath+0x358/0x418 jbd2_log_do_checkpoint+0x31c/0x438 [jbd2] __jbd2_log_wait_for_space+0xfc/0x2f8 [jbd2] add_transaction_credits+0x3bc/0x418 [jbd2] start_this_handle+0xf8/0x560 [jbd2] jbd2__journal_start+0x118/0x228 [jbd2] __ext4_journal_start_sb+0x110/0x188 [ext4] ext4_do_writepages+0x3dc/0x740 [ext4] ext4_writepages+0xa4/0x190 [ext4] do_writepages+0x94/0x228 __writeback_single_inode+0x48/0x318 writeback_sb_inodes+0x204/0x590 __writeback_inodes_wb+0x54/0xf8 wb_writeback+0x2cc/0x3d8 wb_do_writeback+0x2e0/0x2f8 wb_workfn+0x80/0x2a8 process_one_work+0x178/0x3e8 worker_thread+0x234/0x3b8 kthread+0xf0/0x108 ret_from_fork+0x10/0x20 So explicitly call cond_resched() in jbd2_log_do_checkpoint() to avoid softlockup. Cc: stable@kernel.org Signed-off-by: Baokun Li Link: https://patch.msgid.link/20250812063752.912130-1-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman

jbd2: stop waiting for space when jbd2_cleanup_journal_tail() returns error

2024-10-10T09:57:50+00:00

commit f5cacdc6f2bb2a9bf214469dd7112b43dd2dd68a upstream. In __jbd2_log_wait_for_space(), we might call jbd2_cleanup_journal_tail() to recover some journal space. But if an error occurs while executing jbd2_cleanup_journal_tail() (e.g., an EIO), we don't stop waiting for free space right away, we try other branches, and if j_committing_transaction is NULL (i.e., the tid is 0), we will get the following complain: ============================================ JBD2: I/O error when updating journal superblock for sdd-8. __jbd2_log_wait_for_space: needed 256 blocks and only had 217 space available __jbd2_log_wait_for_space: no way to get more journal space in sdd-8 ------------[ cut here ]------------ WARNING: CPU: 2 PID: 139804 at fs/jbd2/checkpoint.c:109 __jbd2_log_wait_for_space+0x251/0x2e0 Modules linked in: CPU: 2 PID: 139804 Comm: kworker/u8:3 Not tainted 6.6.0+ #1 RIP: 0010:__jbd2_log_wait_for_space+0x251/0x2e0 Call Trace: add_transaction_credits+0x5d1/0x5e0 start_this_handle+0x1ef/0x6a0 jbd2__journal_start+0x18b/0x340 ext4_dirty_inode+0x5d/0xb0 __mark_inode_dirty+0xe4/0x5d0 generic_update_time+0x60/0x70 [...] ============================================ So only if jbd2_cleanup_journal_tail() returns 1, i.e., there is nothing to clean up at the moment, continue to try to reclaim free space in other ways. Note that this fix relies on commit 6f6a6fda2945 ("jbd2: fix ocfs2 corrupt when updating journal superblock fails") to make jbd2_cleanup_journal_tail return the correct error code. Fixes: 8c3f25d8950c ("jbd2: don't give up looking for space so easily in __jbd2_log_wait_for_space") Cc: stable@kernel.org Signed-off-by: Baokun Li Reviewed-by: Jan Kara Link: https://patch.msgid.link/20240718115336.2554501-1-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman

ext4: fix incorrect tid assumption in jbd2_journal_shrink_checkpoint_list()

2024-10-10T09:57:48+00:00

commit 7a6443e1dad70281f99f0bd394d7fd342481a632 upstream. Function jbd2_journal_shrink_checkpoint_list() assumes that '0' is not a valid value for transaction IDs, which is incorrect. Don't assume that and use two extra boolean variables to control the loop iterations and keep track of the first and last tid. Signed-off-by: Luis Henriques (SUSE) Reviewed-by: Jan Kara Link: https://patch.msgid.link/20240724161119.13448-4-luis.henriques@linux.dev Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman

ext4: fix incorrect tid assumption in __jbd2_log_wait_for_space()

2024-10-10T09:57:47+00:00

commit 972090651ee15e51abfb2160e986fa050cfc7a40 upstream. Function __jbd2_log_wait_for_space() assumes that '0' is not a valid value for transaction IDs, which is incorrect. Don't assume that and invoke jbd2_log_wait_commit() if the journal had a committing transaction instead. Signed-off-by: Luis Henriques (SUSE) Reviewed-by: Jan Kara Link: https://patch.msgid.link/20240724161119.13448-3-luis.henriques@linux.dev Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman

jbd2: remove unused function '__cp_buffer_busy'

2023-08-04T20:32:29+00:00

The code calling function '__cp_buffer_busy' has been removed, so the function should also be removed. silence the warning: fs/jbd2/checkpoint.c:48:20: warning: unused function '__cp_buffer_busy' Reported-by: Abaci Robot Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=5518 Signed-off-by: Yang Li Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230714025528.564988-4-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o

jbd2: check 'jh->b_transaction' before removing it from checkpoint

2023-08-04T20:32:23+00:00

Following process will corrupt ext4 image: Step 1: jbd2_journal_commit_transaction __jbd2_journal_insert_checkpoint(jh, commit_transaction) // Put jh into trans1->t_checkpoint_list journal->j_checkpoint_transactions = commit_transaction // Put trans1 into journal->j_checkpoint_transactions Step 2: do_get_write_access test_clear_buffer_dirty(bh) // clear buffer dirty，set jbd dirty __jbd2_journal_file_buffer(jh, transaction) // jh belongs to trans2 Step 3: drop_cache journal_shrink_one_cp_list jbd2_journal_try_remove_checkpoint if (!trylock_buffer(bh)) // lock bh, true if (buffer_dirty(bh)) // buffer is not dirty __jbd2_journal_remove_checkpoint(jh) // remove jh from trans1->t_checkpoint_list Step 4: jbd2_log_do_checkpoint trans1 = journal->j_checkpoint_transactions // jh is not in trans1->t_checkpoint_list jbd2_cleanup_journal_tail(journal) // trans1 is done Step 5: Power cut, trans2 is not committed, jh is lost in next mounting. Fix it by checking 'jh->b_transaction' before remove it from checkpoint. Cc: stable@kernel.org Fixes: 46f881b5b175 ("jbd2: fix a race when checking checkpoint buffer busy") Signed-off-by: Zhihao Cheng Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230714025528.564988-3-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o

jbd2: fix checkpoint cleanup performance regression

2023-08-04T20:32:05+00:00

journal_clean_one_cp_list() has been merged into journal_shrink_one_cp_list(), but do chekpoint buffer cleanup from the committing process is just a best effort, it should stop scan once it meet a busy buffer, or else it will cause a lot of invalid buffer scan and checks. We catch a performance regression when doing fs_mark tests below. Test cmd: ./fs_mark -d scratch -s 1024 -n 10000 -t 1 -D 100 -N 100 Before merging checkpoint buffer cleanup: FSUse% Count Size Files/sec App Overhead 95 10000 1024 8304.9 49033 After merging checkpoint buffer cleanup: FSUse% Count Size Files/sec App Overhead 95 10000 1024 7649.0 50012 FSUse% Count Size Files/sec App Overhead 95 10000 1024 2107.1 50871 After merging checkpoint buffer cleanup, the total loop count in journal_shrink_one_cp_list() could be up to 6,261,600+ (50,000+ ~ 100,000+ in general), most of them are invalid. This patch fix it through passing 'shrink_type' into journal_shrink_one_cp_list() and add a new 'SHRINK_BUSY_STOP' to indicate it should stop once meet a busy buffer. After fix, the loop count descending back to 10,000+. After this fix: FSUse% Count Size Files/sec App Overhead 95 10000 1024 8558.4 49109 Cc: stable@kernel.org Fixes: b98dba273a0e ("jbd2: remove journal_clean_one_cp_list()") Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230714025528.564988-2-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o

jbd2: fix a race when checking checkpoint buffer busy

2023-07-11T03:09:21+00:00

Before removing checkpoint buffer from the t_checkpoint_list, we have to check both BH_Dirty and BH_Lock bits together to distinguish buffers have not been or were being written back. But __cp_buffer_busy() checks them separately, it first check lock state and then check dirty, the window between these two checks could be raced by writing back procedure, which locks buffer and clears buffer dirty before I/O completes. So it cannot guarantee checkpointing buffers been written back to disk if some error happens later. Finally, it may clean checkpoint transactions and lead to inconsistent filesystem. jbd2_journal_forget() and __journal_try_to_free_buffer() also have the same problem (journal_unmap_buffer() escape from this issue since it's running under the buffer lock), so fix them through introducing a new helper to try holding the buffer lock and remove really clean buffer. Link: https://bugzilla.kernel.org/show_bug.cgi?id=217490 Cc: stable@vger.kernel.org Suggested-by: Jan Kara Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230606135928.434610-6-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o

jbd2: Fix wrongly judgement for buffer head removing while doing checkpoint

2023-07-11T03:09:21+00:00

Following process, jbd2_journal_commit_transaction // there are several dirty buffer heads in transaction->t_checkpoint_list P1 wb_workfn jbd2_log_do_checkpoint if (buffer_locked(bh)) // false __block_write_full_page trylock_buffer(bh) test_clear_buffer_dirty(bh) if (!buffer_dirty(bh)) __jbd2_journal_remove_checkpoint(jh) if (buffer_write_io_error(bh)) // false >> bh IO error occurs << jbd2_cleanup_journal_tail __jbd2_update_log_tail jbd2_write_superblock // The bh won't be replayed in next mount. , which could corrupt the ext4 image, fetch a reproducer in [Link]. Since writeback process clears buffer dirty after locking buffer head, we can fix it by try locking buffer and check dirtiness while buffer is locked, the buffer head can be removed if it is neither dirty nor locked. Link: https://bugzilla.kernel.org/show_bug.cgi?id=217490 Fixes: 470decc613ab ("[PATCH] jbd2: initial copy of files from jbd") Signed-off-by: Zhihao Cheng Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230606135928.434610-5-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o